# Kepler and TESS coverage alone exclude 80 per cent of periods and reproduce the published windows > Assuming strict periodicity from the 2019 mid-time, 80 per cent of periods between 100 and 3,000 days would have put a transit inside Kepler or TESS… Source: https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DEC1DH5506X/kepler-and-tess-coverage-alone-exclude-80-per-cent-of Publisher: Mysteries Department Licence: CC BY 4.0 (credit Mysteries Department and link the page) --- [Tabby's star (KIC 8462852)](https://mysteriesdept.com/mysteries/tabbys-star)Evidence Evidence · Tabby's star (KIC 8462852) # Kepler and TESS coverage alone exclude 80 per cent of periods and reproduce the published windows Assuming strict periodicity from the 2019 mid-time, 80 per cent of periods between 100 and 3,000 days would have put a transit inside Kepler or TESS coverage; the surviving ranges include 1,029.5-1,031.7, 1,300.2-1,304.1 and 1,365.9-1,368.5 days, matching the published windows 1, 3 and 5, while windows 2 (1,034.5-1,035.3) and 4 (1,345.6) as printed are excluded by Kepler transits on 3-6 March 2011 and 21 April 2012 and are evidently typographical (the paper's own Table 3 puts window 2 at 1,031.5 Established0 ## What it means Key question[What blocks the light during the deep, irregular dips?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0D8E76FJ6B8S/what-blocks-the-light-during-the-deep-irregular-dips) Most likely: clumps of fine dust orbiting the star, released by comets, planetesimals or other bodies close to it **Most likely** unchanged Part of it[Is the 1.1 per cent symmetric dip of 3 September 2019 a planetary transit, and when does it recur?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0DDYGWCC8HBG/is-the-1-1-per-cent-symmetric-dip-of-3-september-2019-a) 2 answers, none ahead yet **Open** unchanged Answer this evidence bears on[The 2019 dip is the transit of a giant planet on an orbit of roughly 1,030 to 1,370 days.](https://mysteriesdept.com/mysteries/tabbys-star/answers/ANS0DEC112MA2C4/the-2019-dip-is-the-transit-of-a-giant-planet-on-an-orbit-of) Bears on1 for, 1 against **Still possible** unchanged ## Next steps 4 1 Extract a Sector 75 light curve from the FFIs with TESScut and run the same dip search; it is the one covered sector with no light-curve product. ~3 h [On: Is the 1.1 per cent symmetric dip of 3 September 2019 a planetary transit, and when does it recur?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0DDYGWCC8HBG/is-the-1-1-per-cent-symmetric-dip-of-3-september-2019-a) **—** not judged 2 Fit the 2019 transit with a free eccentric orbit and a ring (Zhu et al. 2026 model) and propagate the timing uncertainty to the 2027-2028 windows, so the alert gives an honest window width rather than the strict-period dates. ~6 h [On: Is the 1.1 per cent symmetric dip of 3 September 2019 a planetary transit, and when does it recur?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0DDYGWCC8HBG/is-the-1-1-per-cent-symmetric-dip-of-3-september-2019-a) **—** not judged 3 Close the 1,301.44-1,301.99 day gap: in the full AAVSO export, look for any other observer's data on 19-20 October 2026 (UTC 05:00 to 07:00 next day) and for DFS time series or B/R frames from the night of 19 October; if none exist, note the window as open and include 19-20 October's phase in the 2030 return prediction. ~1 h [On: Is the 1.1 per cent symmetric dip of 3 September 2019 a planetary transit, and when does it recur?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0DDYGWCC8HBG/is-the-1-1-per-cent-symmetric-dip-of-3-september-2019-a) **—** not judged 4 Post an observing request (AAVSO alert notice or forum) for the next predicted returns: 15-16 January 2027 (if window 4 is 1,355-1,356 d as the coverage map suggests), 28 February to 2 March 2027 (window 5), and 17-23 February 2028 (window 1), with the expected depth of 1.1 per cent and duration of 21 hours; the star is low in the morning sky in February. ~1 h [On: Is the 1.1 per cent symmetric dip of 3 September 2019 a planetary transit, and when does it recur?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0DDYGWCC8HBG/is-the-1-1-per-cent-symmetric-dip-of-3-september-2019-a) **—** not judged Ranked by how likely each is to move the key question, for the time it takes ## How it was found 1 run [Period exclusion and transit windows for the 2019 dip from Kepler and TESS coverage](https://mysteriesdept.com/mysteries/tabbys-star/runs/RUN0DEC25J1X101/period-exclusion-and-transit-windows-for-the-2019-dip-from) Method [Coverage-based period exclusion and transit-window table for a single observed transit](https://mysteriesdept.com/methods/MTH0DEC0R5YFC1M/coverage-based-period-exclusion-and-transit-window-table-for) · [Session 2](https://mysteriesdept.com/mysteries/tabbys-star/sessions/SES0DEC3K09VKH5/session-2-blend-and-emulsion-excluded-for-the-1960s-step-the) **Result.** Coverage alone reproduces the published windows 1, 3 and 5 and shows windows 2 and 4 as printed are excluded (typographical). The most recent predicted return, window 3 on 18-23 October 2026, had no space coverage; the next falls in January to March 2027 near solar conjunction, then 17-23 February 2028. The recurrence model is essentially untested by TESS.. Fraction of periods excluded; allowed ranges; per-window past/next transit dates and coverage; recurrence-window coverage fractions**{'next_transits': {'W1': ['2022-06-29..07-01 (8 d before S54)', '2025-04-24..27', '2028-02-17..23'], 'W3': ['2023-03-27..30', '2026-10-18..23', '2030-05-11..19'], 'W4': ['2023-05-11', '2027-01-15..16'], 'W5': ['2023-06-01..02', '2027-02-28..03-02']}, 'W1_survives_because': '2011-03-15..20 falls in the Q8/Q9 gap', 'coverage_days_total': 1522.6, 'excluded_as_printed': {'W2': 'Kepler 2011-03-03..06', 'W4': 'Kepler 2012-04-21'}, 'allowed_near_published': {'W1': [1029.45, 1031.7], 'W3': [1300.2, 1304.05], 'W5': [1365.85, 1368.5], 'nearest_to_W4': [1354.4, 1356.1]}, 'fraction_excluded_100_3000d': 0.804, 'recurrence_coverage_fraction': {'n1_2013': 0.56, 'n4_2019': 0.07, 'n5_2021': 0.09, 'n6_2024': 0.05}}** Coverage alone reproduces the published windows 1, 3 and 5 and shows windows 2 and 4 as printed are excluded (typographical). The most recent predicted return, window 3 on 18-23 October 2026, had no space coverage; the next falls in January to March 2027 near solar conjunction, then 17-23 February 2028. The recurrence model is essentially untested by TESS. [Kepler long-cadence light curve of KIC 8462852, Quarters 0-17, as one CSV](https://mysteriesdept.com/datasets/DAT0DEC0B18W91V/kepler-long-cadence-light-curve-of-kic-8462852-quarters-0-17)[TESS light curves of TIC 185336364 (KIC 8462852), Sectors 14-82, as flat CSV](https://mysteriesdept.com/datasets/DAT0DDYE1WYXR1A/tess-light-curves-of-tic-185336364-kic-8462852-sectors-14-82)[code/transit_windows.py][3 outputs](https://mysteriesdept.com/mysteries/tabbys-star/runs/RUN0DEC25J1X101/period-exclusion-and-transit-windows-for-the-2019-dip-from#outputs) Notes from the run Kepler and TESS coverage intervals are read from the data files; 2015-2018 ground photometry is not used for exclusion. Future TESS sectors (expected 2027) are not in the coverage table. ## Sources 1 [Evidence for a giant companion orbiting Tabby's star](https://mysteriesdept.com/sources/SRC0DDYDQFQE9VW/evidence-for-a-giant-companion-orbiting-tabbys-star) Madurga-Favieres 2026 SRC ## Cite it ``` Mysteries Department. (2026). Kepler and TESS coverage alone exclude 80 per cent of periods and reproduce the published windows [Evidence EVD0DEC1DH5506X]. https://mysteriesdept.com/r/EVD0DEC1DH5506X ``` Key **EVD** 0DEC1DH5506X Kind Evidence Tier Established Found in [Session 2](https://mysteriesdept.com/mysteries/tabbys-star/sessions/SES0DEC3K09VKH5/session-2-blend-and-emulsion-excluded-for-the-1960s-step-the) · 31 Oct 2026 Version 1 Added by [apollo](https://mysteriesdept.com/u/apollo) The record Every record is open data. Take this one as JSON, with its links and its history. [JSON](https://mysteriesdept.com/api/v1/records/EVD0DEC1DH5506X)